I go 



SCIENCE. 



[Vol. XI. No. 



His conclusions are as follows : i. Leprosy has existed to a con- 

 siderable extent in this country during the past twenty years ; 2. 

 The tendency is for the disease to increase, not only from immi- 

 gration, but also from the occurrence of sporadic cases ; 3. It is a 

 contagious disease, and may be transmitted from parent to off- 

 spring ; 4. Transmission probably takes place, in some instances 

 at least, through inoculation ; 5. Segregation has been proved to be 

 the only sure means of freeing a country from its ravages ; 6. It is 

 the duty of the government to establish central leper- hospitals or 

 isolated settlements for the treatment of those afflicted, and for the 

 protection of the community at large. 



Burning Garbage. — Sanitarians in this country have for 

 many years been considering the practicability of destroying the 

 garbage of a city by fire. The city of Milwaukee has been a pio- 

 neer in the movement to demonstrate the feasibility of this method 

 of disposal. The commissioner of health of that city, in a recent 

 letter to the Saiiiiary Nczus, gives some interesting facts concern- 

 ing the experience of that city. " For more than five months our 

 garbage has been consumed to a dry, inodorous ash. A test of the 

 cost of consuming the garbage was made on Dec. 27, with the fol- 

 lowing result: the amount received and consumed was 40,215 

 pounds, and the fuel required was 5,000 pounds, being 4.3 cents per 

 hundred pounds of garbage consumed, — a result highly gratifying 

 when we consider that on that date there was a large quantity of 

 snow and ice mixed with the garbage." 



BOOK-REVIEWS. 



Volcanoes and Earihqicakcs. By SAMtJEL Kneeland. Boston, 

 Lothrop. 8°. 



The present volume is mostly a description of ascents of vol- 

 canoes and of remarkable eruptions which the author has witnessed, 

 or the description of which he has taken from reliable sources. 

 Thus the book has some value as a book of travel, or for making 

 clear the phenomena of volcanic action to the general reader. The 

 author has visited so many volcanic regions, — the Hawaiian Is- 

 lands, Iceland, the Mediterranean Sea, Japan, and the islands of 

 south-eastern Asia, — that he is well able to give a description of 

 the peculiarities of the various volcanoes ; and the principal value of 

 the book lies in the vividness of the descriptions, which is due to 

 the personal knowledge of the author of so great a part of the 

 earth's surface. He wisely abstains from a long discussion of the 

 theory of volcanic phenomena, as this would be out of place in a 

 popular book like this, but merely enumerates the various theories 

 that are now held by geologists. The latter part of the book con- 

 tains descriptions of remarkable earthquakes. 



Lectures on the Physiology of Plants. By JULIUS voN Sachs. 



Tr. by H. Marshall Ward. Oxford, Clarendon Pr. 8°. (New 



York, Macmillan, $8.) 

 VoN Sachs's text-book of botany has always been regarded as 

 one of the best in any language, and no better proof of this can be 

 given than the fact that four editions have been published and 

 exhausted. Dr. Sachs was requested by the publishers of his te.\t- 

 book, and also by his botanical friends, to prepare a fifth edition. 

 This he declined to do, and gives his reasons therefor in the follow- 

 ing language : " It is an old experience, that, while one works up 

 with pleasure a second and even third edition of a comprehensive 

 work, frequent repetition eventually becomes inconvenient or even 

 painful to the author. Having experienced this sufficiently with 

 the fourth edition, I was unable to make up my mind to a fifth. 

 Apart from other circumstances, I was driven to this, to an impor- 

 tant extent, by the progressive development of my scientific con- 

 victions." He adds, that his mode of comprehending important 

 questions of the physiology of plants had undergone changes in 

 various directions, and that for several years the wish had been 

 taking a more and more definite form, in his mind, to set forth the 

 most important results of the physiology of plants in such a man- 

 ner that not only students, but also wider circles, should be inter- 

 ested in them. Believing that this object could be better attained 

 by a freer form of exposition than that of a text-book, he determined 

 to present the subject in the form of lectures. This determina- 



tion has resulted in the ' Vorlesungen iiber Pflanzen-physiologie." 

 which Professor Ward has translated in a most admirable manner. 

 The volume consists of forty-six lectures, arranged in six parts. 

 These latter are, i. Organography; 2. The external conditions of 

 vegetable life, and the properties of plants ; 3. Nutrition ; 4. 

 Growth; 5. Irritability; 6. Reproduction. It is impossible to give 

 more than this brief outline of a book which embraces so many and 

 such varied topics as are treated in the eight hundred and two 

 pages of text. Professor Sachs has succeeded in his undertaking, 

 to a degree which is exceptional, to produce in this series of lectures 

 a treatise adapted to the wants of the skilled botanist and the edu- 

 cated man, whose studies have been in other directions, but whose 

 desire for a knowledge of the physiology of plants has hitherto 

 been unsatisfied. The subject is made much more intelligible by 

 the four hundred and fifty-five woodcuts with which the book is 

 embellished ; while the elaborate index, covering thirty-three pages. 

 makes it exceedingly valuable for reference. 



Photography applied to Surveying. By Henrv A. REED. U.S..-\. 

 New York, Wiley. 4°. §2.50. 



The author gives a concise sketch of the successful experinienis 

 made in photographic surveying, and sets forth the methods now 

 in use. The book is principally founded on the publications of 

 Frenchmen who have paid particular attention to developing this 

 branch of the art of surveying. The author's discussions of the 

 various methods are clear and concise. The principle of photo- 

 graphic surveying is the same as that of ordinary surveying. .Sta- 

 tions are occupied by the photographer ; and the angles, which are 

 generally measured by the theodolite, are measured on the photo- 

 graphic negative. For this purpose the camera is provided with a 

 level, and the distance between the sensitive plate and the object- 

 glass is kept constant. The horizon is marked on the negative, 

 and a measurement of distances serves for finding the azimuths 

 and elevations of objects. In making the photographs, various in- 

 struments are used, — the ordinary camera, with a wide-angle ob- 

 jective ; a camera in which a cylindrical sheet of sensitive paper 

 takes the place of the plate, and in which the photograph is pro- 

 duced by turning the camera around its axis; or the photographic 

 plane table. In the latter the photographic view is represented on 

 a horizontal surface, the rays from the object being reflected either 

 by a triangular glass prism or by a spherical convex reflector. 

 The author justly claims great advantages for these methods, 

 among which the most valuable are the cheapness of field-work, 

 and the great amount of information contained in the photographic 

 views. Setting aside geodetic operations, photographic surveying is 

 undoubtedly the cheapest and best method wherever the principal 

 object is to attain, not the greatest possible accuracy, but the fullest 

 amount of information in the shortest possible time. Therefore 

 the publication is very valuable and welcome, giving a concise re- 

 view of the advantages and results of this method, which is still 

 very little used in this country. We may be allowed to add a few 

 remarks on this subject, in addition to Lieutenant Reed's full dis- 

 cussion. Photographic surveying cannot attain the same accuracy 

 as ordinary surveying; but the errors are so small, that for tertiary, 

 and even for secondary triangulation, it meets all demands. Us 

 greatest value, however, lies in the full material it furnishes for 

 constructing the orographic features of a country. No topographer, 

 however experienced he may be, can draw contour lines as well 

 from sketches and a few fixed points as he can construct them from 

 photographic surveys. The number of elevations that may be de- 

 termined by this method is practically without limit. Another im- 

 portant use of photographic work is the facility it affords for re- 

 surveying tracts of land, particularly in regard to changes in culture. 

 Deforestation, roads, the extent of agricultural land, etc., are shown 

 on the photographs, and may readily be inserted in maps without 

 fear of omissions. Thus it will be of the greatest utility for the 

 questions of a census. Lieutenant Reed touches only slightly upon 

 its use in reconnaissance work. For this purpose the cylindric ar- 

 rangement gives the greatest satisfaction, principally as it dispenses 

 with the use of bulky and heavy photographic plates, which are 

 difficult to carry. For topographic work of this kind, the use of 

 photography, supplemented by sketches made by \!{\i camera lucida, 

 gives by far the best results. \ concluding chapter of the book 



